The author of 《Chemistry of the “”insoluble red”” woods. I. Pterocarpin and homopterocarpin》 were McGookin, Alexander; Robertson, Alexander; Whalley, Wm. B.. And the article was published in Journal of the Chemical Society in 1940. Synthetic Route of C12H12O4 The author mentioned the following in the article:
Owing to the insoluble nature of their coloring matters in warm H2O, red sandalwood, camwood, barwood and narrawood have been classified as “”insoluble red”” woods to distinguish them from the “”soluble red”” woods of the logwood type. Since these woods invariably contain the colorless constituents pterocarpin (I) and homopterocarpin (II), they have been studied as an approach to the structure of the dyes. Finely powd. barwood (Baphia nitida Lodd) (300 g.), extracted with 2.5 l. boiling CCl4 for 6 h., the filtered extract concentrated to 37-40 cc. at a temperature not above 50°, 1.5 g. of red solid filtered off, the viscous red liquid dissolved in 20 cc. 96% alc. and the precipitate which seps. fractionally crystallized from 96% EtOH, give 0.15 g. I and 1 g. II, C17H16O4, m. 87°, [α]546120.5 -236.6° (CHCl3, c 0.898 g. in 100 cc.) (cf. Leonhardt and Oechler, C. A. 30, 1372.1). II sublimes unchanged at 80°/0.1 mm. II is extremely sensitive to mineral acids and is stable to boiling EtOH-NaOH; HO or CO groups could not be detected. Oxidation of II with KMnO4 in aqueous Me2CO gives a mixture of 5,2-MeO(HO2C)C6H3OCH2CO2H (IIA) and 2,4-HO(MeO)C6H3CO2H (IIB), indicating the presence of an O-mono-Me resorcinol nucleus and of the system -C.O.CH2C- in II. Catalytic reduction of II in EtOH or AcOH with Pd-C gives l-dihydrohomopterocarpin (III), R = 2,4-HO(MeO)C6H3, m. 154°, [α]546120 -12.7° (EtOH, c 0.295); this is also formed by the Clemmensen reduction of II; the Me ether (IV) m. 61° (cf. Dieterle and L., C. A. 23, 2245). Oxidation of III with CrO3 in AcOH gives dihydrohomopterocarpone (V), orange, m. 177.5-8.5°; oxime, m. 229°. KMnO4 oxidation of III in Me2CO gives 7-methoxy-3-chromancarboxylic acid (VI), m. 149°; the yellow concentrated H2SO4 solution exhibits a brilliant green fluorescence. Reduction of V with Zn and AcOH gives the quinol(?), m. 145°. Oxidation of IV with KMnO4 in Me2CO gives an isoflavanone (VII), R = 2,4-(MeO)2C6H3, m. 127° (oxime, m. 185.5°; 2,4-dinitrophenylhydrazone, red, m. 184°); further oxidation of VII in 2 N NaOH with KMnO4 gives a compound, C15H9O3(OMe)3(?), m. 178°. The 4′-position for the MeO group in III is preferred, although it has not been definitely established. I m. 164.5° [α]546120.5 -207.5° (CHCl3, c 0.530). Hydrogenation of I in AcOH with Pd-C gives a dihydro derivative (VIII), m. 140°, [α]546121 -19.5° (EtOH, c 1.714), which also results on Clemmensen reduction of I; Me ether (IX), m. 106.5°. Oxidation of I with KMnO4 in aqueous Me2CO gives a mixture of IIA and IIB, with a small amount of a neutral product, m. 272°. VIII gives VI with KMnO4 in aqueous Me2CO and with CrO8 in AcOH there results a yellow resinous product which with 2,4-(O2N)2C6H3NHNH2 gives a compound, C23H18O10N4, maroon, m. 202-3° (decomposition). KMnO4 oxidation of IX yields a ketone, C16H10O4(OMe)2, m. 118-19°, whose 2,4-dinitrophenylhydrazone, scarlet, m. 248°. Thus, I appears to differ from II in having a methylenedioxy group. 4-O-Methyl-β-resorcylaldehyde in 8% aqueous KOH, added to ClCH2CH2CO2H in aqueous NaHCO3, gives β-(5-methoxy-2-formylphenoxy)propionic acid, m. 159°; 2,4-dinitrophenylhydrazone, m. 241.5°; semicarbazone, m. 218° (decomposition); oxidation with alk. KMnO4 gives β-(5-methoxy-2-carboxyphenoxy)propionic acid, m. 143°; Me ester, b95 78-80°. The acid, Ac2O and AcONa, refluxed 1 h. at 145°, give 7-methoxy-Δ3-chromene-3-carboxylic acid, m. 201°; the yellow concentrated H2SO4 has an intense green fluorescence; catalytic reduction gives VI. 2,5-OHC(MeO)C6H3OCH2CO2Et gives a 2,4-dinitrophenylhydrazone, crimson, m. 176.5°; cyclization of the ester with EtONa in EtOH gives Et 6-methoxy-2-coumaronecarboxylate (X), m. 87°; it gives a cherry-red and then a purple H2SO4 reaction; acidification of the alk. liquor gives 2,5-OHC(MeO)C6H3OCH2CO2H, yielding a 2,4-dinitrophenylhydrazone, light red, m. 273°. The free acid from X m. 206°, having a crimson and then a brilliant purple H2SO4 reaction; PCl5 in CHCl3 gives the acid chloride (XI), b15 165°, m. 101°. XI in absolute ether at -10° with anhydrous HCN and a mixture of C5H5N and ether gives the nitrile, pale yellow, b1.5 162°, m. 101°; this could not be converted into the corresponding pyruvic acid. XI and CH2N2 in ether give the diazoketone, pale yellow, m. 90-1° (slight decomposition); with NH4OH and AgNO3 in dioxane there results the amide, m. 148°, of 6-methoxy-2-coumaroneacetic acid, m. 104°. In addition to this study using Ethyl 6-methoxybenzofuran-2-carboxylate, there are many other studies that have used Ethyl 6-methoxybenzofuran-2-carboxylate(cas: 50551-57-0Synthetic Route of C12H12O4) was used in this study.
Ethyl 6-methoxybenzofuran-2-carboxylate(cas: 50551-57-0) belongs to benzofurans.Synthetic Route of C12H12O4Benzofurans containing one furan ring that have been implicated as psychoactive recreational drugs include 6-(2-aminopropyl)benzofuran (6-APB), 5-(2-aminopropyl)benzofuran (5-APB), 5-(2-ethylaminopropyl)benzofuran (5-EAPB), and 5-methylaminopropylbenzofuran (5-MAPB).
Referemce:
Benzofuran – Wikipedia,
Benzofuran | C8H6O – PubChem